1. Field of the Invention
The present invention relates to a vacuum cleaner, in particular, a dust collector for capturing dust sucked together with air.
2. Description of Related Art
There is known a vacuum cleaner with a dust collector detachable from a main unit that is capable of taking air and dust sucked from a suction section, thereby capturing the dust sucked together with air into the dust collector and allowing air to pass through the dust collector to discharge from the main unit. The air sucked into the dust collector chamber is guided to a dust collection chamber through a guide pipe and then passes through a filter to be discharged. The dust sucked into the dust collector together with air is captured by the filter while the air passes through the filter and is accumulated in the dust collection chamber. The dust accumulated in the dust collection chamber can be readily removed by detaching the dust collector from the main unit and performing a prescribed operation.
However, in this kind of the vacuum cleaner, when the dust is accumulated in the dust collection chamber to some extent, the flow of air that moves toward the filter through the dust collection chamber is deteriorated, thereby lowering suction force. Then, Patent Publication No. 3460832 discloses a dust collector with a bypass passage for separating part of air sucked into the dust collector and bypassing a dust collection chamber to discharge the air by forming a vent hole in the middle of a guide pipe.
FIGS. 15A and 15B are views showing an example of a guide pipe 141 provided in a conventional dust collector. Specifically, FIG. 15A is a side view of the guide pipe 141 and FIG. 15B is a sectional view of the guide pipe 141.
With reference to FIGS. 15A and 15B, the guide pipe 141 includes an inlet pipe 142 forming an inlet port 112 of the dust collector and a lead-in pipe 143 for leading air and dust flowing from the inlet pipe 142 to a dust collection chamber.
The inlet pipe 142 is provided with a tube 142A shaped in a truncated cone, one and the other sides of which are opened in the axial direction, and a flange 142B projecting from an edge of the tube 142A on its smaller diameter side in the radial direction. One end of a hose, the other end of which is connected to a suction section of a vacuum cleaner, is fitted into the tube 142A of the inlet pipe 142.
The lead-in pipe 143 is shaped in a circular pipe having a bent 146 curved or crooked substantially at right angle along the path and is equipped with a filter section 155 spreading in the shape of a truncated cone at an end coupled to the inlet tube 142. A plurality of vent holes 147 are formed on a circumferential face of the filter section 155 and each of the vent holes 147 is covered with a filter 150. A flange 155A projecting in the radial direction is formed on an edge on a larger diameter side of the filter section 155 (an edge connected to the inlet pipe 142 of the lead-in pipe 143). A circular packing 144 is engaged with the flange 155A and the flange 142B of the inlet pipe 142 abuts on the packing 144, thereby bonding the inlet pipe 142 to the lead-in pipe 143 with a bonded part being sealed.
Most of the air sucked from the inlet pipe 142 is led to the dust collection chamber together with dust through the lead-in pipe 143 and part of the air flows out of the lead-in pipe 143 through the vent holes 147. At this time, dust contained in the air passing through the vent holes 147 is captured by the filter 150. A bypass passage is formed outside of the vent holes 147 and the air flowed out of the vent holes 147 bypasses the dust collection chamber to be discharged. Thus, since the flow of air can be ensured, suction force can be prevented from deterioration.
However, with the conventional configuration described above, an inner diameter of the guide tube is narrowed at the filter section, thereby causing pressure loss in the vicinity of the filter section. Accordingly, there is a possibility that the suction force may be decreased, thereby lowering suction performance.
Furthermore, since the filter section is extended in the shape of a truncated cone, arrangement of the filter section requires relatively large space. Since the space for arranging the dust collector is restricted, when the space for arranging the filter section is made larger, the dust collection chamber needs to be made smaller. In this case, an amount of dust that can be stored in the dust collection chamber becomes smaller. Furthermore, the suction force is lowered when the dust collection chamber is filled with the dust. With the conventional configuration, however, the suction force is decreased in a relatively short period of time, resulting in poor suction performance.
In addition, since the filter is extended in a direction intersecting with a flowing direction of air and dust in the guide tube, dust is easy to adhere to the filter, and in the case where a foreign particle having high gravity (such as a metal piece) flows into the guide pipe, the foreign particle can strike against the filter, thereby damaging the filter. When dust is adhered to the filter, the flow of air to the bypass passage is worsened and the suction force is lowered. Furthermore, when the filter is damaged, a foreign particle can flow into the bypass passage, clogging the passage. Accordingly, in either case, suction performance can be worsened.